Memory is a factor that directly affects the cost of all sorts of digital devices, from computers, to synth keyboards, to storage media. Take the example of a synth keyboard which stores its on-board sounds as samples in built-in memory. While longer, higher resolution samples sound much better, they also require more memory to store. A fairly straightforward formula can be used to calculate digital memory:
Time x Sample Rate x Resolution x Channels = Memory Note the following:
1. Time, the length of the digital recording, is in seconds. 2. Sample Rate, the number of amplitude readings taken per second, is a frequency (in hertz). 3. Resolution, how accurately an amplitude level can be recorded, depends on the number of bytes (8 bits) allotted to each sample. With n bits, an amplitude can be recorded on any of 2n levels . 4. Channels, usually one (monaural) or two (stereo).
As an example, let’s figure out how much memory it takes to record a minute of audio at conventional CD-quality specifications. The time, at one minute, is 60 seconds. The sampling rate for CDs is 44,100 hertz. The sample resolution is two bytes since the specification for CDs samples is 16-bits. Finally, since CDs are in stereo, they use two channels. Here’s the memory calculation using the formula:
60 secs. x 44,100 hertz x 2 bytes x 2 channels = 10,584,000 bytes
As you can see, one minute of CD quality audio requires about 10.5 megabytes of memory storage.
A fairly straightforward formula can be used to calculate digital memory:
Time x Sample Rate x Resolution x Channels = Memory
Note the following:
1. Time, the length of the digital recording, is in seconds.
2. Sample Rate, the number of amplitude readings taken per second, is a frequency (in hertz).
3. Resolution, how accurately an amplitude level can be recorded, depends on the number of bytes (8 bits) allotted to each sample. With n bits, an amplitude can be recorded on any of 2n levels .
4. Channels, usually one (monaural) or two (stereo).
As an example, let’s figure out how much memory it takes to record a minute of audio at conventional CD-quality specifications. The time, at one minute, is 60 seconds. The sampling rate for CDs is 44,100 hertz. The sample resolution is two bytes since the specification for CDs samples is 16-bits. Finally, since CDs are in stereo, they use two channels. Here’s the memory calculation using the formula:
60 secs. x 44,100 hertz x 2 bytes x 2 channels = 10,584,000 bytes
As you can see, one minute of CD quality audio requires about 10.5 megabytes of memory storage.